Mine Drainage and Surface Mine Reclamation. Volume II: Mine Reclamation, Abandoned Mine Lands and Policy Issues. Vol. II. Pittsburgh, PA: U.S. Bureau of Mines, 1988 Apr; :111-117
The vegetation on 20 non-resoiled bituminous strip mines in northwestern Pennsylvania was surveyed to study the factors which account for variability in the quantity and quality of the vegetation. The sites ranged in age from 12 to 41 years. All had acid spoils, and 15 had been planted with trees before abandonment. Two revegetation patterns were discovered. One group of 10 sites had high tree densities (2,333 stem/ha average), high basal area (13.5 m2/ha average), and were at various stages of forest development. As these sites aged, bare soil disappeared and litter increased. The second group had lower tree densities (1,186 stem/ha average), lower tree growth (2.6 m2/ha average), and were not developing into forest communities. Instead, the spoils were characterized by patchy vegetation and had large open areas. As these sites aged, bare soil disappeared, but only lichens and mosses increased. The different revegetation patterns were not generally a result of the success or failure of tree-planting efforts. Densities of living planted trees did not differ significantly between the groups. The extent of colonization by volunteer trees, primarily aspens, was the most important determinant of high tree density and eventual forest development. Development of a forest community on the poorly vegetated sites is largely dependent on the recruitment of new trees into open areas. Except for sporadic colonization of grass clumps by red maple, very little recruitment of new trees was occurring. If methods to stimulate colonization of these areas by volunteer trees could be developed, a low-cost reclamation option might be available for thousands of poorly vegetated sites in Appalachia.